1. Field of the Invention
The present invention relates to a sheet retaining device for a ring binder, and more particularly, to a sheet retaining device having a plurality of longitudinally extending ribs located thereon which increase the sheet retaining device's resistance to deformation.
2. Description of the Background Art
Various ring binders are known in the art which have a paper sheet retaining device attached to a cover member by a plurality of fasteners, such as rivets 60, which extend through the cover member 62 and which are deformed, for example, by punching, to securely and permanently fix the paper retaining device to the cover member. Such an arrangement is shown in FIG. 15. The ring binder may be shipped in an assembled condition, which takes up enormous space in the packaging thereof, resulting in higher shipping costs.
Alternatively, the ring binder may be shipped in an unassembled condition with the cover members packaged separately from the sheet retaining devices for subsequent assembly by the consumer. When packing the sheet retaining devices together, a first sheet retaining device is placed directly over a second sheet retaining device such that the rings of the first sheet retaining device engage the upper member of the second sheet retaining device, and vice-versa. Typically, the upper member is simply a curved metal strip. Such an arrangement is shown in FIGS. 13 and 14.
A disadvantage associated with such packaging of conventional sheet retaining devices is that the upper members become damaged in transit. One reason is that the ring members, which are convex, are placed in contact with the upper members, which are also convex. Such an arrangement is unstable, and allows the ring members to slide on the surface of the upper members. This results in visible scratching of the surface of the upper member due to lateral sliding. Further, compressive forces placed on the upper member by the contacting ring member during transit cause the upper member to deform or dent, since the upper member is typically just a curved strip of metal with no mechanism for preventing such deformation.
As a result of such scratching and denting, the sheet retaining devices are received by the customer in an unsightly condition, and are therefore unusable. This results in waste both in an unusable product and the lost shipping costs.
Another method of shipping the sheet retaining devices is to package the sheet retaining devices with a plurality of separator strips located therebetween, as shown in FIGS. 16-25. However, the use of such separator strips creates a larger overall package, because the distance between the upper and lower sheet retaining devices is increased, as well as the overall length of the package due to the placement of the separator strips between adjacent rings of the sheet retaining device. Such wasted space is costly, and the use of the separator strips adds to the overall cost of the package and the labor involved in properly locating the separator strips between the adjacent sheet retaining devices.